I have 9 garages 2 armory and 4 mint I hold 360 in garage but I also use the reinforcement commander and that allows me to have 1.7 mil reinforcement if you are making a trap base this works great. (Heli def focus)

If you are building your main fighting base only use one mint and one armory, the rest garages. As you get bigger you can switch garages for armories. I am 1.1B power and still have 12 lvl 22 garages. I also keep about 4m t1 of my def unit as a meat shield. Right now I'm trying to decide if I swap more garages for armories...it is hard to give up health when I do so many camp battles.